This is a shared instrumentation proposal to NIH and NSF, for purchase of an Illumina Lab Genotyping System. This bead array based system provides the opportunity to conduct high throughput and low cost genotyping of single nucleotide polymorphisms (SNPs), with a capacity of up to 600,000 genotypes per day. We have assembled a group of NIH and NSF funded investigators who will make immediate use of this system for their funded projects. The user group is mainly centered at UCLA, UC Irvine, UC San Diego, and University of Southern California, and is therefore termed The Southern California Genotyping Consortium. Other identified major users are, however, spread across the United States. The instrumentation will have two main purposes: 1) genome wide association studies, particularly in recently founded population isolates; 2) intensive investigation of selected genome regions in a wide variety of populations and different organisms. The capacity of the instrument is sufficiently great to accommodate all of the needs of the major users and to permit recruitment of new users. We have outlined a financial, organizational, and management plan for the instrumentation that indicates that we will be able to maintain the production of large numbers of genotypes and to handle the massive data flow, at a very low cost to users, with financial support almost entirely covered from recharges. Substantial institutional investment will enable the purchase and set-up of the instrumentation. We envision that this genotyping system will have enormous benefits for the genetic investigation of common diseases, for comparative genetic and genomic studies, and for the understanding of evolutionary processes. We also envision that the proposed consortium will foster new collaborations within and between the constituent institutions. [unreadable] [unreadable]